The human heart is hollow muscular organ having four pumping chambers separated by four heart valves. The mitral and tricuspid valves, present at the left and right atrioventricular junctions, open and close in response to a pressure gradient during each cardiac cycle of relaxation and contraction to control the flow of blood to a particular region of the heart.
These valves are comprised of a dense fibrous ring known as the annulus, leaflets or cusps attached to the annulus, and a complex of chordae tendinae and papillary muscles securing the leaflets. The size of the leaflets or cusps is such that when the heart contracts the resulting increased blood pressure formed within the ventricular cavity forces the leaflets towards the arterial cavity. As a result, the leaflets or cusps come in apposition to each other thereby closing the atrio-ventricular passage.
Natural defects and heart disease are common causes of valvular dysfunction within the heart of a patient. One common example of valvular dysfunction occurs, when the annulus becomes excessively dilated or the valve geometry results in ineffective valve closure, which results in regurgitation. Due to the increased diameter of the annulus, the leaflets or cusps fail to meet during systolic contraction, thereby resulting in the regurgitation of blood during ventricular contractions. As such, sufficient back pressure exists within the chambers of the heart capable of forcing some blood flow to traverse the atrioventricular junction from the ventricle to the atria.
One manner of repairing this problem involves surgically implanting a prosthetic implant, often referred to as “annuloplasty rings”, about the dilated annulus, thereby restoring the annulus to the normal size and shape and allowing the valve leaflets to function normally. Commonly, a surgeon positions the annuloplasty ring near the valve annulus and sutures the device in place.
One approach to correcting or remodelling the valve annulus has required the implantation of a rigid annuloplasty ring. Typically, an annuloplasty ring having the desired internal diameter is positioned near the heart valve and sutured in place. As a result, the diameter of the valve is reduced to the diameter of the annuloplasty ring.
The previously published US patent application 2005/055087 A1, describes methods for “Introducing a stabilizing member beneath one or more heart leaflets” inconjunction with an optional “Second stabilizing member . . . introduced above the (valve) leaflets for further stabilization”. A catheter is utilised to deliver the stabilizing member(s), as well as “Hydraulically driven tethered anchors” which provide for cinching of the dilated annulus, through adjustment of the tether. The anchors are separate entities not attached to the tether. The tether is merely guided in an eyelet of each of the anchors. An annuloplasty ring is not described. After deployment, the device is not retrievable from the patient other than by open chest surgery. This may be a major disadvantage when the device is malpositioned.
In US 2007/0016287 an “Implantable device is provided for controlling shape and/or size of an anatomical structure or lumen.” Wherein the implantable ring utilises an adjustment means to regulate the size of the annulus and is attached to the tissue through drawing of a deployment suture which releases tissue anchors which previously were flush to the annulus. The number of anchor elements is limited as the total number of anchor elements is defined by the specific length of each of the adjacent anchoring elements when flush. This also means that the maximum anchoring depth of the anchor when released is limited. Thus, there is a need to improve reliability of anchoring. Moreover, the annuloplasty ring may not comprise a collar element around the ring, sometimes desired to improve sealing of the ring against the annulus, as the anchors would be hindered from their movement. After deployment, the device is not retrievable from the patient other than by open chest surgery. This may be a major disadvantage when the device is malpositioned.
Although these provide possible treatment modalities, improved treatment means are required to provide enhanced tissue attachment in-conjunction with greater ease of regulating annular size to limit the procedure time and safeguard against misplacement which can lead to e.g. embolization.